Which are the four types of sensory nerve fibers listed in the material?

Which are the four types of sensory nerve fibers listed in the material?

• A. A-alpha, A-beta, A-gamma
• B. A-delta, C-fiber
• C. A-alpha, A-beta, A-delta
• D. A-alpha, A-beta, A-gamma, C-fiber

Answer: (A)

Understanding sensory nerve fibers starts with recognizing they’re categorized by speed and myelination. The four key sensory fibers are A-alpha, A-beta, A-delta, and C-fibers. A-alpha fibers are the largest and fastest, carrying proprioceptive information from muscles and joints (and contributing to motor control). A-beta fibers are next in size and conduct quickly, transmitting light touch and pressure. A-delta fibers are smaller but still myelinated, conveying fast, sharp pain and cold temperature. C-fibers are unmyelinated and slow, carrying dull, aching pain and warmth. A-gamma fibers, by contrast, are motor fibers from gamma motor neurons that adjust muscle spindle sensitivity, not sensory fibers. So the four sensory fiber types are A-alpha, A-beta, A-delta, and C-fibers.

Understanding sensory nerve fibers starts with recognizing they’re categorized by speed and myelination. The four key sensory fibers are A-alpha, A-beta, A-delta, and C-fibers. A-alpha fibers are the largest and fastest, carrying proprioceptive information from muscles and joints (and contributing to motor control). A-beta fibers are next in size and conduct quickly, transmitting light touch and pressure. A-delta fibers are smaller but still myelinated, conveying fast, sharp pain and cold temperature. C-fibers are unmyelinated and slow, carrying dull, aching pain and warmth. A-gamma fibers, by contrast, are motor fibers from gamma motor neurons that adjust muscle spindle sensitivity, not sensory fibers. So the four sensory fiber types are A-alpha, A-beta, A-delta, and C-fibers.